This invention relates to chargers for rechargeable batteries and more particularly to a simple, inexpensive indicator for indicating when cells in the charger are being charged.
In a prior art consumer charger such as shown in U.S. Pat. No. 4,009,429, the disclosure of which is hereby incorporated by reference herein, no mechanism is provided to indicate when the charger is actually providing charge current to cells disposed in the charger for charging. This has been found to be undesirable because the operator after loading cells in the charger and attaching the charger to a power supply cannot immediately identify whether the cells in the charger are being charged. With this system the determination of whether the cells are being charged can only be made by testing or using the cells after being connected to the charger for a few hours. The cells would not be charged, for example, if one of the cells is defective, if one or both cells is installed with its polarity reversed, if one or both of the cells is making poor electrical contact with the charger terminals, if no power is supplied to the charger, if the charger is defective or if only one cell is positioned in the charger.
In prior art chargers, it is known to use an electric lamp to indicate the flow of a charging current. Such chargers are disclosed in U.S. Pat Nos. 3,245,726, 3,421,142 and 3,746,961. Such an indicator has been found to be disadvantageous in miniaturized, wall-mounted charges because it must be energized by the charging circuit and thus a larger transformer is required to energize the load provided by the cell(s) and the indicator. All of these factors add both cost and weight to the charger, both of which are critical in such chargers.
Accordingly, it is an object of this invention to provide a charger with the indicator which does not require electrical energization by the charging circuit.
It is another object of this invention to provide a charger with a small, light weight indicator.
It is another object of this invention to provide a charger with an indicator which gives a rapid indication of whether charge current is being supplied to the cells mounted in the charger.